The invention relates to ankle replacement prostheses and systems, as well as associated surgical instruments and procedures. The present invention is more specifically towards intramedullary ankle joint replacements.
Until the early to mid 1970's, patients with injured or diseased ankle joints commonly resulting from rheumatism, or degenerative or traumatic arthritis, had few options when their ankle joints failed. The most common procedure to help these patients regain some use of their ankle was obliteration of the joint by fusion, a procedure that is still commonly used today. Fusion, however, rendered the ankle stiff and generally immobile relative to the lower leg, resulting in limited use and additional stresses on the knee and hip joints.
Probably the first reported use of total ankle prosthesis was by Buckholz in 1969. The medical community recognized that such ankle replacement led to largely increased use of the ankle joint because the replacement permitted ankle ranges of motion which generally attempted to mimic the natural human joint. Since that time, ankle replacement prostheses have become increasingly common in use and improved in design.
Ankle fractures are particularly common in people having bone disease, such as osteoporosis. Geriatrics, particularly woman, are very susceptible to ankle fractures, and the prognosis after fracture is generally poor, even with the use of a prosthesis. In general, currently used prostheses do not afford the necessary flexibility required for an ankle joint and recovery can be slow and arduous. The fusing together of bones or bone segments required and carried out with prior prostheses limits the ability of the ankle joint to completely heal properly, particularly with those who may have limited mobility prior to the ankle fracture.
Stability and weight bearing are other issues that are more important when replacing an ankle joint as opposed to other joints. For example, hip, shoulder, or knee joints are not required to bear the load that is required from an ankle joint. Consequently the use of replacement devices for these other joints does not necessarily translate to possible joints for an ankle joint.